In reply to The Bantam: Don't use Petzl, they're almost certain to pack up within the year, utter rubbish (I've had two go on me in 18 months and others in my club have fared similarly). Hope lights or Black Diamond, every time.

I do a fair bit on the fells at night in winter, I have used the Alpkit Gamma, Petzl Myo XP and Silva X Trail. The Gamma is great although perhaps a little underpowered, the Petzl is good if you get one without the connector faults, the Silva has a stronger beam, but gets through batteries quite quickly.

I am not a fan of the very powerful lights such as some of the Hope head torches, as running in a ball of super bright white takes a lot of the enjoyment out of it for me. This winter I will be running with the Silva with the Gamma as a backup.

In reply to The Bantam: It really depends what you're going to use it for. I've had a tikka XP for a few years and it's been great, just about powerful enough on new batteries to run on difficult ground. The Vicar's comments about petzl being unreliable are unusual, there have been plenty problems with the myo XP but apart from that they have a decent reputation. I've certainly abused mine and it's still going well. It's also one of the few products that never seem to get returned faulty to the shop (apart from the myo XP!).
If your running on non-technical terrain a self contained torch will be adequate and more reliable than one with a separate battery pack. There's plenty out there to look at, the most prominent being from BD, petzl and silva and all good.
If you want something for more technical terrain the more powerful torches come with a remote battery pack (either at the back of the head or loose), the silva trail runner is good value, also the petzl RXP and black diamond icon are popular.
There's loads of information about, you can't really go wrong with most of the decent brands these days.

In reply to The Bantam:
Alpkit Gamma the best value medium brightness headtorch.

If you want to move to something brighter then I'd recommend the LED Lenser H7R - very powerful on full beam ( 160 Lumens ), but can be turned down when not needed on full, still pretty cheap, rechargeable battery ( but can also take AA so you can carry spares )

In reply to The Bantam:
I've got a Fenix HP11 which was relatively cheap compared to similar units, and looks a little ungainly, but is absolutely brilliant in use. Easily bright enough to run over technical ground on full power, but obviously dims to a reasonable level too.

In reply to steelbru: I have the LED lenser H7 not the R. And it is good! it can be turned up or down and focused for different fields of vision. BUT its does tend to drop down on its mount when running over ruff ground and then all you can see if your nose. I solved this by putting it on upside down!